Unkown Fax Result Status

I keep on getting an "Unknown" Status Result on my outgoing fax. My recepient says he's going to acknowledge the email once he got it but I've been trying to sit and wait to make sure it'll send for hours now but it's still the same. Tried contacting support but none can give me a definite answer. Can you guys help? I was always told that the person I am faxing don't have a fax number.